Deck Height 00 CR 125

[Jman271]

Hey guys, EG, just wondering if you knew off the top of your head what the max amount of deck clearance you have seen w/ regard to a 00 CR 125? I have a measured deck clearance of .55mm which seems excessive to me, this is w/a OEM base gasket and a Wiseco Pro-lite piston. I was thinking that the deck,(compared to some other CR's I have seen) seem to be about .005 or so. The squish test came back around 1.25mm. I am thinking that maybe I should machine the base of the cyl to get a zero deck, then recess the head as much or slightly less to give me around 1mm of squish. I will have to cc the head to see what I have in there as to keep the CR w/i spec if I take the head down and adj bowl volume. WDYT? Thanks guys-

 

[bclapham]

0.5mm deck height with a 0.5mm head recess sounds about right to me.

check this out

http://www.ericgorr.com/twostktech/bigbore_specs.htm

 

[Jman271]

Hmmm, your are right according to those specs. The recess he speaks of is for the squish, but not the deck. I wonder if this is all based on a zero deck. Just kinda weird, the bike seems to be down on power, but all checks out far as blow down, exh opening etc. The last few CR's (01-02) I have done had less deck, more like .005", and more recessed squish on the stock head. So things just seemd a bit backwards here. I would have liked to have looked into some 03-05 CR 125's but no one around here rides them as they are dogs in the motor dept compared to the YZ, YZF, SX etc. I will do some more figuring to see what can be done. Thanks- Maybe when EG gets a sec, he will post, but I know he is busy. :laugh:

 

[Rich Rohrich]

Maybe when EG gets a sec, he will post, but I know he is busy. :laugh:

It might be a while, the shop is pretty busy this week.

 

[bclapham]

Jman- 0.5mm deck and 0.5mm recess sounds about right- even if the ports are off + or - 0.25mm, it wont change much from my expereience- its only the difference of a thin gasket for example.

 

[marcusgunby]

The problem with the 00-02 IMO is the pv doesnt come close enough to the piston-it looks to me like the 05 parts would fit and they are much better.

 

[Jman271]

Yeah, I guess you are right, those dimensions yeild 1mm or so. Marcus, I haven't seen the 05 125 flappers, maybe they could slap in? You think they have a tighter tolerance, around 1mm? Worth checking out, I'll see if they will fit in. I would like to see these flappers made of a lighter material like aluminum, they seem heavy and bulky.

 

[marcusgunby]

They look just like the 02 style but fit real close to the piston.